1. Field of the Invention
The present invention relates to an IP (Internet Protocol) telephone access system especially to an IP telephone access system applied to a fixed telephone service, a customer's terminating device and an IP telephone access method.
2. Description of the Prior Art
Preferably, the conventional telephone number system being the fixed telephone number (0AB-J number) is also used for an IP telephone by using a fixed telephone service. That is because the phone number of the fixed telephone (0AB-J number) infiltrates deeply in the life of people such that it is possible to specify the place of dispatch of an urgent message, and it is possible to identify the area of the phone because of the geographically identified characteristic.
Further, that is because the existing fixed telephone (analog telephone or ISDN (Integrated Services Digital Network) telephone) can be replaced to the IP telephone without changing the subscriber's number which is used for the fixed telephone.
On the other hand, it is necessary for the fixed telephone to prevent the use of the phone number (0AB-J number) beyond the geographically identified area. In other words, it is necessary for the fixed telephone to prevent the use of the phone number of the fixed telephone in Osaka after having been transferred from Tokyo. For instance, Japanese Patent application laid open No. 2003-324486 discloses, as an IP telephone access system for the conventional fixed telephone service, the art which realizes the transfer of a telephone without changing its telephone number.
A description will be given of the structure of a conventional communication network system with reference to FIG. 1. Referring to FIG. 1, in the conventional communication network system, there is provided an exchange (a) 51 and an exchange (b) 52 on a common channel signaling network 57 and a software switch (a) 60 and a software switch (b) 61 on an IP network 66.
The exchange (a) 51 includes a fixed telephone terminal (a) 53 and a fixed telephone terminal (b) 54, and the exchange (b) 52 includes a fixed telephone terminal (c) 55 and a fixed telephone terminal (d) 56.
The software switch (a) 60 includes an IP telephone terminal (a) 62 and an IP telephone terminal (b) 63, and the software switch (b) 61 includes an IP telephone terminal (c) 64 and an IP telephone terminal (d) 65.
There are provided a Media Gateway Controller (hereinafter referred to as MGC) (a) 58 and an MGC (b) 59 on the boundary between the common channel signaling network 57 and the IP network 66. The MGC (a) 58 and the MGC (b) 59 convert a call connecting signal of the common channel signaling network 57 to that of the IP network 66 or convert the call connecting signal of the IP network 66 to that of the common channel signaling network 57.
A description will be given of the operation of the transfer of a telephone without changing its telephone number with reference to FIG. 2. Referring to FIG. 2, an exchange (a) 111 has MTP=a as its MTP (Message Transfer Part) address on the common channel signaling network and has a fixed telephone terminal (a) 114 having its telephone number 03-1111-0001. An exchange (b) 112 has MTP=b as its MTP address and included a fixed telephone terminal (b) 115 having had its telephone number 03-2222-0002 before having been transferred.
An MGC 116 has MTP=c as its MTP address and 10.10.10.1 as its IP address on the IP network. A software switch 118 has 100.100.100.1 as its IP address and includes an IP telephone terminal (a) 120 having 100.100.100.3 as its IP address and an IP telephone terminal (b) 121 having 100.100.100.2 as its IP address after being transferred.
In the case that the fixed telephone terminal (b) 115 having its telephone number 03-2222-0002 is transferred to the IP telephone terminal (b) 121 having its IP address 100.100.100.2, it is necessary that the transfer of the fixed telephone terminal (b) 115 and the forwarding address thereof have been set in the exchange (b) 112 including the fixed telephone terminal (b) 115.
In a subscriber's number management table 113 in the exchange (b) 112, the state corresponding to the subscriber's number 03-2222-0002 is set at “transfer” and its forwarding MTP address is set at MTP=c. In an “incoming number”-“account” management table 117 in the MGC 116, the account corresponding to the incoming number 03-2222-0002 is set at BBB@domainA. In an account management table 119 in the software switch 118, the IP address 100.100.100.2 corresponding to the account BBB is set.
In this state, when a phone call is made to 03-2222-0002 from the fixed telephone terminal (a) 114, a call connecting signal is transferred to the exchange (b) 112 via the exchange (a) 111. In the subscriber's number management table 113 in the exchange (b) 112, the forwarding address of 03-2222-0002 is set at the MTP address being MTP=c, and thus, the call connecting signal is transferred to the MGC 116 having the MTP address being MTP=c. Then, the “incoming number”-“account” management table 117 in the MGC 116 transfers the call connecting signal to the software switch 118 including the account BBB@domainA.
In the software switch 118, the account management table 119 transfers the call connecting signal to the IP telephone terminal (b) 121 having the IP address 100.100.100.2 corresponding to the account BBB, and therefore the call connection becomes possible. In this way, even when the fixed telephone terminal (b) 115 is transferred to the IP telephone terminal (b) 121, communication can be established with the old subscriber's number 03-2222-0002.
In the above described conventional communication network system, the exchange has the management table having the subscriber's number and the forwarding address, and the media gateway controller has the management table having the incoming number and the account. With these two management tables, the account management table in the software switch coordinates the subscriber's number and its IP address and transfers the call for the subscriber to its IP address. Therefore, after having completed the operation of the transfer of a telephone without changing the telephone number, the conventional communication network system still needs the exchange and the media gateway controller, and also needs the management table in the software switch for coordinating the account and its IP address, and thus, the operation becomes wasteful and complicated.
Moreover, in the conventional communication network system, for newly receiving an IP telephone service, in the case of using the fixed telephone number (0AB-J number), the exchange and the media gateway controller are necessary and also the management table in the software switch is necessary for coordinating an account and its IP address from the same reason as above, and thus, the operation becomes wasteful and complicated.